go/types, types2: report type name in comp. literal error, if possible
When reporting an error for the element type of a struct literal, use
the element type's type name rather than it's underlying/core type.
Also, combine error reporting for invalid composite literal types in
one place, at the end.
Fixes #68184.
Change-Id: I1f407d5403777948da9a0eca95aacc1389f4bd44
Reviewed-on: https://go-review.googlesource.com/c/go/+/595075
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Robert Griesemer <gri@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Tim King <taking@google.com>